In the natural environment, rainfall sinks into soil,f ilters through it, and eventually finds its way to streams, ponds, lakes, and underground aquifers. The built environment, however, seals the surface. Rainwater and snowmelt become runoff which may contribute to flooding. Contaminants are washed from surfaces directly into waterways without undergoing the filtration Mother Nature intended.

When used for parking lots, roads, walking/biking paths, and other applications, porous pavements can turn runoff into infiltration and restore the hydrology of a site or even improve it. Porous pavements conserve water, replenish aquifers, and protect streams.

A typical porous pavement has a surface that looks similar to conventional asphalt, but has tiny pores that allow the water to drain directly through it into an underlying stone recharge bed.